Process of making chlorosulfonic acid.



- AUGUST KLAonsA nHEmANN voLLia Ro, or sALBxE, GERMANY.

PROCESS MAKING QHLOROSULFONIG ACID.

No Drawing.

1 To all whom it may concern:

react with pure sulfuric anhydrid.

- Be. it known that we, AUGUST KLAcEs and HERMANN VQLLBERG, bothsubjects of the German Emperor, and residents of Salbke, in the Provinceof Saxony, Kingdom of Prussia, German Empire, have invented new anduseful Improvements in the Process of Manufacturing Chlorosulfonic Acid,of which .the following is a full, clear, and exact specification.

In the manufacture of chlorosulfonic acid it has hitherto been thecustom to pass hydrochloric acid gas into ,a solution of sulfuricanhydrid in sulfuric acid (pyrosulfuric acid or fuming sulfuric acid)and to isolate the chlorosulfonic acid by distillation, or to cause dryhydrochloric acid ga eqtlo first process has the disadvantage that itinvolves a distillation for the separation of the chlorosulfonic acidand the second process also requires a distillation for obtainingsulfuric anhydrid in the gaseous or liquid form from fuming sulfuricacid. Moreover, when-liquid. sulfuric anhydrid is used, the hydrochloricacid gas must contain some 90-per cent; of hydrogen; chlorid, becausethe sulfuric anhydrid is very easily carried forward by any air that maybe contained in the hydrochloric acid gas, and is apt to polymerize inthe pipes, thereby choking them. Again, when the liquid sulfuricanhydrid is used, great caution must be observed, because cooling theliquid mass is a very critical operation owing to the ease with whichthe liquid anhydrid changes to.

the solid polymer, which, unlike the liquid anhydrid, has but littletendency to react with hydrochloric acid; there are formed channels inthe solidified mass through which the hydrogen chlorid passes. Accordingto the present invention all these disadvantages are overcome by causingthe reaction between the sulfuric anhydrid and the hydrochloric'acid gasto occur in chlorosulfonic acid as a .solvent. In this acid liquid orgaseous sulfuric anhydrid is very easily soluble, while the solidpolymer is nearly insoluble. At the beginning of the process thesolution of sulfuric anhydrid in Specification of Letters Patent.

' Patented Jan. 2, 1912.

Application filed m 25, 1910. Serial No. 573,641.

chlorosulfonic acid is cooled down to about 0 C, at which temperaturethe solid anhydr d does not separate. chlorlc acld gas is introducedinto such a When hydrosolution, it is eagerly absorbed with forma--tion'of chlorosulfonic acid. The gas may contain air, and the solutionmay be cooled to such a degree that no sulfuric" anhydrid is carriedaway by the air. During the process 1t 1s only necessary to prevent theincrease 1n temperature. of the solution caused by the introduction ofthe hydrochloric acid gas from exceeding 30 C. no special cooling beingtherefore necessary. It, is also practicable to pass hydrochloric acidgas and gaseous sulfuric anhydrid together into 'chlorosulfonic acid,and in this case the anhydrid may be mixed with air;

indeed the mixture. coming directly from the contact apparatus andcontaining 7 per cent. by volume of the anhydrid, may be used. Whenperforming the process in this manner special cooling is not necessarythe hydrochloric acid gas andthe gaseous. sulfuric anhydrid being simplyintroduced into an apparatus similar to a Glover or Gay-Lussac tower, inwhich the ichlorosuh fomc acid then dissolvesthe sulfuric anhydrid 'andis acted upon by the hydrochloric acid gas. In either case purechlorosulfonic acid is obtained directly.

The process has the advantage over those previously applied, that nodistillation is necessary and that gases containing air, as they arenormally obtained, may be used.

It is only necessary to have acertain quantity of chlorosulfonic acid,made in any manner, for starting the operation. The process has also theadvantage that it can easily be made continuous, since thechlorosulfonic acid can be removed as it is formed.

What we claim 1s:

1. The hereinbefore described process of manufacturing 'chlorosulfonicacid, which process consists in introducing hydrochloric acid gas andsulfuric anhydrid into chlorosulfonic acid.

2., The hereinbefore described process of manufacturing chlorosulfonicacid, which process consists in introducing hydrochloric acid gas into asolution of sulfuric anhy- In testimony, that we claim the foregoing 10drid in chlorosulfonic acid while avoiding as our invention, we havesigned our names the prelsenfie of iufuricd'acid. in presence of twosubscribing Witnesses.

3. T e erein e ore escribed rocess of 5 manufacturing chlorosulfonicacid, which processconsists in introducing hydrochloric acid gas andgaseous sulfuric anhydrid into Witnesses: chlorosulfonic acid at amoderate tempera- LEoPoLD RUPRUTTUS, ture. WILHELM BOLDT.

